Fig. 2: Study sites and the contribution of pyrogenic carbon (PyC) to soil organic carbon across tropical savannas in Kruger National Park, South Africa.

A Geographic location of Kruger National Park within South Africa, on the African continent. The mean annual burned area is represented as a percentage of the burnable land area per year (% year⁻¹) in each 0.25° × 0.25° grid cell from 2001 to 2020. Data are from the Global Fire Emission Database (GFED5)¹². The base map is modified from Natural Earth. B Spatial distribution of 253 Veld Condition Assessment (VCA) sites overlaid on a map showing fire frequency (fires/year) across tropical savannas in Kruger National Park. Fire frequency was calculated based on fire records from 1941 to 2023. The Kruger National Park shapefile was provided by South African National Parks Scientific Services. C Images illustrating three VCA sites, including their mean annual rainfall, soil clay content, grass biomass, and fire frequency. D Boxplot comparing the percentage of PyC in soil organic carbon (SOC) (%) across global savannas synthesized from the literature (n = 197) and savannas within Kruger National Park, South Africa (n = 253). The box represents the interquartile range from the 25^th to the 75^th percentile of the data, with the line inside the box indicating the median value. Whiskers extend to the highest and lowest values within 1.5 times the interquartile range. Individual data points are shown as jittered dots. Note that PyC measurements for global savannas were obtained from varying soil depths and determined using different methodological approaches. Source data are provided as a Source Data file.